- Project Description For The Case Study Problem Change The Power Requirement To 40 Horsepower Design The Intermediate S 1 (724.15 KiB) Viewed 52 times
- Project Description For The Case Study Problem Change The Power Requirement To 40 Horsepower Design The Intermediate S 2 (429.02 KiB) Viewed 52 times
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Project Description For the case study problem, change the power requirement to 40 horsepower. Design the intermediate shaft, including complete specification of the gears, bearings, keys, retaining rings, and shaft. A mechanical design company wishes to provide off-the-shelf speed reducer (two-stage, compound reverted gear train such as shown in figure below) in various capacities and one speed ratio to sell to a wide variety of target applications. The marketing team has determined a need for one of these speed reducers to satisfy the following customer requirements. 1 11 Figure: A compound reverted gear train Design Requirements Power to be delivered: 22 kW Input speed: 55 rev/s Output speed: 3-4 rev/s Targeted for uniformly loaded applications, such as conveyor belts, blowers, and generators Output shaft and input shaft in-line Base mounted with 4 bolts Continuous operation 6-year life, with 8 hours/day, 5 days/wk Low maintenance Competitive cost Nominal operating conditions of industrialized locations Input and output shafts standard size for typical couplings The following product specifications provide an appropriate framework for this design task. Design Specifications Power to be delivered: 22 kW Power efficiency :> 99 % Steady state Input speed: 45 rev/s Maximum Input speed: 55 rev/s Steady state output speed: 3-4 rev/s Usually low shock levels, occasional moderate shock Input and output shafts extend 6 in outside gearbox Input and output diameter tolerance: $ 0.030 mm Input and output shafts in-line: concentricity = 0.130 mm, alignment = 0.002 rad Maximum allowable loads on input shaft: axial, 250 N; transverse, 550 N Maximum allowable loads on output shaft: axial, 330 N; transverse, 3330 N Maximum gearbox size: 400 mm x 400 mm base, 700 mm height Base mounted with 4 bolts Mounting orientation only with base on bottom 100% duty cycle Maintenance schedule: lubrication check every 3000 hours; change of lubrication every 8000 hours of operation; gears and bearing life > 15,000 hours; infinite shaft life; gears, bearings, and shafts replaceable Access to check, drain, and refill lubrication without disassembly or opening of gasket joints. Manufacturing cost per unit: < $ 500 Production: 15,000 units per year Operating temperature range: -15° to 70° C Sealed against water and dust from typical weather Noise: < 90 dB from 1 meter
Project Outline: 0- Cover Page 1- Design Sequence for Power Transmission 2- Power and Torque Requirements 3- Gear Specifications 4- Shaft Layout 5- Force Analysis 6- Shaft Material Selection 7- Shaft Design for Stress 8- Bearing Selection 9- Key and retaining Ring Selection 10- Final Analysis Part 1: Problem Specs. Design the intermediate shaft and its components, taking into account the other shafts as necessary (apply your knowledge of Ch. # 7) Part 2: Speed, Torque, and Gear Ratios Determine appropriate tooth counts to reduce the input speed of 55 rev/s to an output speed within the range 3rev/s < 00 < 4 rev/s. Once final tooth counts are specified, determine values of: (a) speeds for the intermediate and output shafts, (b) Torques for the input, intermediate and output shafts, to transmit 15 kW. Part 3: Gear Specs. Specify appropriate gears, including pitch diameter, diametral pitch, face width, and material. Achieve safety factors of at least 1.2 for wear and bending. Part 4: Shaft Layout Prepare a sketch of the gearbox (utilizing your recent knowledge of Solideworks Lab. [CAD]) sufficient to determine the axial dimensions. In particular, estimate the overall length, and the distance between the gears of the intermediate shaft, in order to fit with the mounting requirements of the other shafts. Part 5: Design for Stress Estimate appropriate diameters for each section of the shaft based on providing sufficient fatigue and static capacity for infinite life of the shaft, with minimum safety factor of 1.5. Part 6: Deflection check Check that deflections and slopes at the gears and bearings on the intermediate shaft are within acceptable ranges. 2 Part 7: Bearing Selection Select appropriate bearings for the intermediate shaft, with a reliability of 99 %. Part 8: Key Design Specify appropriate keys for the two gears on the intermediate shaft to provide a factor of safety of 2. The gears are to be custom bored and keyed to the require specifications.